Hepatitis B virus causes liver disease. A significant proportion of infected patients develop chronic hepatitis leading to liver damage and subsequent hepatocarcinoma. Hepatitis B infection is characterized by several distinctive serological and immunological responses. The temporal profiles of infection can serve as a useful guide to monitoring the course of disease and also provide serological correlation with the disease's progress (see, e.g., Elgouhari (2008) Cleveland Clinic J. Med. 75:881 and Juszczyk (2010) Vaccine 18:S23)
Hepatitis B virus contains two major viral proteins, the surface antigen (HBsAg) and the core antigens (HBcAg). Upon infection, HBsAg becomes detectable first, followed by the appearance of anti-HBc IgM generated by the host. Anti-HBs antibodies appear months after the disappearance of HBsAg, and remain detectable indefinitely. During the “window period” (when there is gap of 16-32 weeks between the appearance of HBsAg and the appearance of anti-HBs), the presence of anti-HBc provides serological evidence of current or recent HBV infection. However, presence of anti-HBc IgM and anti-HBc (IgM and IgG) does not indicate either the resolution of infection or protective immunity. The appearance of anti-HBs and the absence of HBsAg indicate the resolution of infection and protective immunity. Furthermore, the presence of anti-HBs in the absence of HBsAg and anti-HBc is indicative of a successfully vaccinated individual.
Hepatitis B serological testing involves measurement of several hepatitis B virus-specific antigens and antibodies. The ability to follow the course of HBV infection and differentiate, e.g., between infection, exposure, and resolution, is important for clinical management. All commercially available Hepatitis B antibody test kits perform one test at a time per reaction vessel. The result of any one given test cannot predict the course or stage of Hepatitis B infection or resolution, so multiple tests must be run, which wastes time, sample, and reagent. Furthermore, a medical provider may not order testing of all relevant HBV markers at once, so that a subject may be called to be tested multiple times. Repeat blood draws are stressful and expensive, and can result in non-compliance and less than optimal treatment. See, e.g., Stramer et al. (2012) Transfusion 52:440.